This invention relates to multiple channel video display apparatus, and more particularly to a programmable system for providing appropriate brightness levels to each of a plurality of channels available for selective display on a CRT (cathode ray tube).
The invention finds application where an operator can control or call up a display from any one of a plurality of video channels or signals. For example, where a multiplicity of radar or computer generated images, e.g., range marks, map video, radar video, test video, synthetic targets, etc., are avaiable for viewing individually on a CRT. Such arrangements are known for aircraft approach, manufacturing plant process control, and the like. Heretofore, such systems have incorporated individual panel mounted manual gain or brightness controls for each channel in the form of selector switches and potentiometers for controlling the brightness of each type of video. These systems have required an inordinately large amount of panel space for individual mechanical control switches and/or potentiometers, and have diverted the operator's time and attention from the principal task. Moreover, the mechanical switches and/or potentiometers have low reliability, resulting in short mean time between failures and excessive down time.